Breathing apparatus

ABSTRACT

In breathing apparatus, inhalation valve means, which allows gas to be inhaled from an inhalation conduit, is situated directly within the path of flow of the exhaled gas so that, in operation, heat is transferred from the exhaled gas to the inhalation valve means. The flow of warm, exhaled gas over the inhalation valve means raises the temperature of the valve means and reduces the likelihood of ice formation.

United States Patent Cheffers et al.

[ 1 June 13, 1972 [54] BREATHING APPARATUS [72] Inventors: Stanley JohnCheffers, Seaford; Michael Harvey Glynn, Hook, both of England SlebeGorman & Company Limited, Chessington, Surrey, England July 31, 1969[73] Assignee:

[22] Filed:

[21 Appl. No.: 846,393

[30] Foreign Application Priority Data Aug. 8, 1968 Great Britain..37,903/68 52 u.s.c| ..128/147 [51] Int.Cl. ..A6lml6/00 [58] FieldofSearch ..l28/147,142,2, 142.3, 146.3, l28/l46.4, 145, 145 A, 142,142.4, 212

[56] References Cited UNITED STATES PATENTS 1,625,419 4/1927 McCaa..128/147 2,875,756 3/1959 Gagnan ..l28/ 147 3,107,669 10/1963 Gross128/147 3,326,214 6/1967 McCoy 128/2 1 2 Primary Examiner-Charles F.Rosenbaum Assistant ExaminerG. F. Dunne Attorney-Holcombe, Wetherill &Brisebois [57] ABSTRACT In breathing apparatus, inhalation valve means,which allows gas to be inhaled from an inhalation conduit, is situateddirectly within the path of flow of the exhaled gas so that, inoperation, heat is transferred from the exhaled gas to the inhalationvalve means. The flow of warm, exhaled gas over the inhalation valvemeans raises the temperature of the valve means and reduces thelikelihood of ice formation.

1 Claim, 3 Drawing Figures PATENTEDJuu 1 3 m2 3.669,109

sum 10F 2 PATENTEUJUM 13 I972 3.669.109 sum 2 or 2 FIG. 3.

BREATHING APPARATUS The invention relates to breathing apparatus andespecially to closed-circuit breathing apparatus.

In closed-circuit breathing apparatus, the circuit includes aninhalation conduit through which gas may be inhaled and an exhalationconduit through which the exhaled gases may pass. Carbon dioxide isremoved from the exhaled gases which are then subsequently recirculatedto the inhalation conduit. Nonretum valves are used in both theinhalation and exhalation conduits to ensure that gas circulates in thecorrect direction. In open-circuit breathing apparatus, on the otherhand, the exhaled gases are discharged.

Problems arise when such breathing apparatus is used in an environmentthat is at a low temperature of the order of C. and below), for example,when the apparatus is used under water, because the exhaled gasescontain a substantial quantity of water vapor. In such environments thetemperature of the gas passing through the inhalation conduit is oftencold enough to freeze any water which may have condensed around theinhalation non-retum valve, impairing the perfonnance of the valve andthe functioning of the apparatus as a whole.

The problem arises especially when liquid oxygen is used as the sourceof oxygen, for the gas to be inhaled is then often at a lowertemperature than the ambient temperature. The problem may also occur,however, when compressed gas is used even though this may be at a highertemperature than that of the surroundings, if the ambient temperatureitself is very low.

This invention provides breathing apparatus which comprises a chamberhaving a users conduit through which a user can inhale gas from thechamber and exhale gas into the chamber, an inhalation conduit, anexhalation conduit, the interior of the inhalation and exhalationconduits being in communication with the interior of the chamber and aportion of the inhalation conduit extending inside the chamber,inhalation valve means arranged to allow gas to enter the chamber oninhalation by a user through the users conduit and exhalation valvemeans arranged to allow gas to leave the chamber through the exhalationconduit on exhalation by the user through the users conduit, theinhalation valve means being situated in the portion of the inhalationconduit within the chamber and directly opposite to the users conduit inthe path of flow of the exhaled gas from the users conduit, whereby, inuse, heat is transferred from the exhaled gas to the inhalation valvemeans.

The flow of warm, exhaled gas directly over the inhalation valve meansraises the temperature of the valve means and reduces the likelihood ofice fonnation. Thus the invention enables the breathing apparatus to beused in environments that are at a relatively low temperature.

Further, water vapor contained in the exhaled gas tends to condense onthe walls of the chamber. The condensed water and saliva when the userrespires through the mouth) collect in the chamber, and the risk ofliquid passing through the inhalation valve to the inhalation conduit isdecreased. The liquid collected in the chamber also acts as a source ofheat, further reducing the tendency of ice formation on and around theinhalation valve means.

If a part of the portion of the inhalation conduit situated within thechamber is also within the path of flow of the exhaled gas, the tendencyof ice formation on the interior of that part of the conduit can also bereduced.

Ice, which may be formed inside the inhalation conduit due, for example,to washing out the apparatus before use, may become detached from thewall of the conduit during use. This ice may slide towards theinhalation valve means and, unless checked, aggravate the freezingproblem at the valve. Advantageously, therefore, a trapping chamber ofannular crosssection is located around the inhalation conduit and theinhalation conduit is in communication with the interior of the trappingchamber through a circumferentially-extending opening in the wall of theconduit, at least a portion of the trapping chamber being located aroundthe portion of the inhalation conduit between the said opening and theinhalation valve means. This annular chamber acts as anice trap andcollects ice sliding along the wall of the inhalation conduit towardsthe inhalation valve means.

Breathing apparatus constructed in accordance with the invention willnow be described by way of example with reference to the accompanyingdrawings, in which:

FIG. 1 is a longitudinal section through the apparatus;

FIG. 2 is a section through the apparatus taken along the line A-A shownin FIG. 1; and

FIG. 3 is a section through a modified portion of the apparatus toenable a mask to be use in place of a mouth-piece.

Referring to the accompanying drawings, the apparatus comprises acylindrical chamber 1 to one end of which is secured an inhalationconduit, indicated generally by the reference numeral 2, and to theother end of which is secured an exhalation conduit 3. The cylindricalchamber 1 is fonned with a connecting pipe 4 which extends radiallyoutwards from the chamber 1 and connects the interior of the chamber 1with a user's conduit which may be a mouth-piece 5 or (as shown in FIG.3) a mask 6.

Both the inhalation conduit 2 and the exhalation conduit 3 comprise aflexible tube secured to the chamber 1, but the inhalation conduit 2also comprises a rigid cylindrical portion 7 located within the chamber1 and extending co-axially with it. The portion 7 of the inhalationconduit 2 is secured to the interior of the wall of the chamber 1 bymeans of a sleeve 8 formed at one end with an inwardly extending annularflange 9 secured at its inner edge to the portion 7. The volume boundedby the sleeve 8 and the flange 9 and the portion 7 forms a trappingchamber 10 of annular cross-section that is open at the end remote fromthe exhalation conduit 3.

A non-retum valve 11 is located within the portion 7 of the inhalationconduit 2 near the end farthest from the annular chamber 10. The valve11 seats against a flange 12 in the portion 7 and, by movement towardsthe end of the portion 7 remote from the annular chamber 10, allows gasto pass from the interior of the conduit 2 to the chamber 1. A spider l3limits movement of the valve 11 in the other direction (see FIG. 2). Asimilar valve 14 is situated near the end of the chamber 1 to which theexhalation conduit 3 is secured. A cylindrical member l5 attached to theinterior surface of the wall of the chamber 1, is of decreased internaldiameter towards the chamber 1 to form a shoulder on which the valve 14seats. The valve 14 only allows gas to pass from the chamber 1 to theexhalation conduit 3 and not in the opposite direction.

In operation, when the wearer inhales, the inhalation valve 11 opens toallow gas to pass from the inhalation conduit 2 into the chamber 1. Onexhalation, the inhalation valve 11 closes and the exhalation vale 14opens. The gas exhaled by the wearer passes over the inhalation valve 11and at least a part of the portion 7 of the inhalation conduit 2. Thegas is relatively warm and will tend to melt any ice on the valve orinterior of the portion 7 and to prevent ice from forming.

Any ice that may fonn on the interior wall of the inhalation conduit 2and become detached from the wall by flexing of the conduit during usewill tend to be collected in the annular chamber 10 surrounding theportion 7 of the conduit 2.

We claim:

1. Breathing apparatus which comprises a chamber having a user's conduitthrough which a user can inhale gas from the chamber and exhale gas intothe chamber, an inhalation conduit, an exhalation conduit, the interiorof the inhalation and exhalation conduits being in communication withthe interior of the chamber and a portion of the inhalation conduitextending inside the chamber, inhalation valve means arranged to allowgas to enter the chamber on inhalation by a user through the user'sconduit, exhalation valve means arranged to allow gas to leave thechamber through the exhalation conduit on exhalation by the user throughthe users conduit, the inhalation valve means being situated in theportion of the inhalation conduit within the chamber and directlyopposite to the users tending opening in the wall of the conduit, and atleast a portion of the trapping chamber being located around the portionof the inhalation conduit between the said opening and the inhalationvalve means.

1. Breathing apparatus which comprises a chamber having a user''sconduit through which a user can inhale gas from the chamber and exhalegas into the chamber, an inhalation conduit, an exhalation conduit, theinterior of the inhalation and exhalation conduits being incommunication with the interior of the chamber and a portion of theinhalation conduit extending inside the chamber, inhalation valve meansarranged to allow gas to enter the chamber on inhalation by a userthrough the user''s conduit, exhalation valve means arranged to allowgas to leave the chamber through the exhalation conduit on exhalation bythe user through the user''s conduit, the inhalation valve means beingsituated in the portion of the inhalation conduit within the chamber anddirectly opposite to the user''s conduit, whereby, in use, heat istransferred from the exhaled gas to the inhalation valve means and atrapping chamber of annular cross-section located around the inhalationconduit, the inhalation conduit being in communication with the interiorof the trapping chamber through a circumferentially-extending opening inthe wall of the conduit, and at least a portion of the trapping chamberbeing located around the portion of the inhalation conduit between thesaid opening and the inhalation valve means.